152 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 6, 



This shell is placed in Professor M'Coy's genus Bolahra on ac- 

 count of the crenulated plate or tooth on the posterior side of the 

 hinge and distinct anterior teeth : these characters connect it also 

 Avith Redonia, from which it differs in its more rhomboidal form, 

 and in wanting entirely the internal plate of that genus, and m the 

 crenulation of the posterior part of the hinge. The condition of the 

 specimens, which are only casts, does not admit of any certainty on 

 the subject. In external form it resembles Pullastra Icevis, Sil. Syst. 



Plate IX. fig. 3. a. Exterior, b. Cast of interior. 



Cypricardia ? Beirensis, n. s. Pl. IX. fig. 16. 



C. testa transversim rhomboideo-ovata, subloevi; antice rotundata, am- 

 pliore ; postice obliqua ; margine venti-ali depresso. 



Shell transverse, ovato-rhomboidal, nearly smooth, with a few 

 inconspicuous lines of growth : front slightly depressed ; anterior 

 end rounded and wider than the posterior end ; ^^dth a long tooth 

 or plate parallel to the posterior side of the hinge-line ; anterior 

 teeth 1 



Length ^, breadth -^^ of an inch. 



From the lower division of the Lower Silurian formation of the 

 Serra de Bussaco. 



This much resembles several of our Upper Silurian species, vnth 

 none of which it can be identified ; the condition of the specimen 

 does not allow the anterior tooth to be made out. 



Plate IX. fig. 16. a. Exterior.' b. Cast of interior. 



MoDioLOPSis elegantulus, n. s. Pl. IX. fig. 15. 



M. test^ oblique transversa, coucentrice lineata ; linea cardinali recta, ura- 

 bonibus mecbis ; antice angustata, postice expansa, Totundata. 



Shell oblique, concentrically striated, with slightly projecting beaks 

 placed in the middle of a long, straight hinge-line ; anterior end 

 narrow, posterior end widened and rounded. 



Length ^, breadth -5 an inch. 



From the lower di\dsion of the Lower Silurian formation at Valeiro 

 do Arruido, in the Serra de Bussaco. 



The single specimen seen of this shell does not show the characters 

 of the hinge ; but in form and in the very forward position of the 

 anterior muscle, it agrees with the shells which Mr. Hall has thrown 

 together under the name of Modiolopsis ; indeed it might pass for a 

 young shell of M. modiolaris but for the position of the beaks, 

 which in that shell are more anterior. 



Plate IX. fig. 15. a. Exterior, b. Internal cast. 



Orthis Ribeiro, n. s. Pl. VIII. fig. 1. 



O. testa concavo-convex^, semi-ovali, angulis productis, striis numerosis- 

 simis dichotomis radiantibus ornata ; valva dorsaU medio convexa, late- 

 raliter depressa ; valva ventrali medjo depressa, lateribus elevata ; area 

 cardinali angusta, laterabter producta. 

 Shell concavo-convex, semi-oval with produced sides ; covered with 



